In order to fasten lids on containers or drums, use is frequently made of locking rings, as a result of which a large number of screw connections are avoided.
Such locking rings usually have a U- or V-shaped cross section and ensure the fixing and sealing of the lid on a drum.
For handling, the open locking rings are provided with one or more turnbuckles which connect the free ends of the locking rings together and pull them together during closing and push them apart during opening. During opening, the locking ring can also assume a larger diameter on account of its internal stress.
A locking ring having a screw lock is known from German laid-open specification DE 197 28 655 A1. A locking ring of the type mentioned at the beginning is sold under the name “Locking ring DN 457” by the company UCON AG Containersysteme KG.
In order to easily and quickly open or close the locking-ring closure, use is frequently made of an electrically or pneumatically driven screwdriver, for example a cordless screwdriver. When the locking-ring closure is opened, the screwing operation should be interrupted before the threaded ring comes into contact with the bearing block. If this does not happen, the threaded ring arranged at the end of the screw frequently strikes the bearing block having the internal thread. In this case, the locking-ring closure receives an impulse, as a result of which it is catapulted up uncontrollably. As a result, there is a risk of injury to bystanders or material damage.
Accordingly, it is desired to avoid this disadvantage of the prior art and to specify a locking-ring closure in which there is no risk that it is catapulted at the end of the opening process when opening is carried out with the aid of a motor-driven screwdriver.